Copyright © 2022 Kenny Levinsen Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice (including the next paragraph) shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. This protocol allows a compositor to suggest for surfaces to render at fractional scales. A client can submit scaled content by utilizing wp_viewport. This is done by creating a wp_viewport object for the surface and setting the destination rectangle set to the surface size before the scale factor is applied. If the surface is not a subsurface, then the buffer size is calculated by multiplying the surface size by the intended scale, rounding the result halfway away from zero. If the surface is a subsurface, then the calculation must account for the surface position when rounding the buffer size. First, add the subsurface position relative to its parent to the surface size, multiplying them by the intended scale and rounding the result halfway away from zero. Second, take the subsurface position relative to its parent, multiplying it by the intended scale and rounding the result halfway away from zero. Finally, subtract the result of the second calculation from the first calculation to get the buffer size. The wl_surface buffer scale should remain set to 1 in both cases. In the compositor, final subsurface positions are calculated by multiplying the position of the subsurface relative to its parent by the intended scale, and rounding the result halfway away from zero. The positions of the parent surfaces, calculated using the same mechanism, are then recursively added to the result. This ensures that position and size rounding is not affected by the movement of parent surfaces. If a surface has a surface-local size of 100 px by 50 px and wishes to submit buffers with a scale of 1.5, then a buffer of 150px by 75 px should be used and the wp_viewport destination rectangle should be 100 px by 50 px. A global interface for requesting surfaces to use fractional scales. Informs the server that the client will not be using this protocol object anymore. This does not affect any other objects, wp_fractional_scale_v1 objects included. Create an add-on object for the the wl_surface to let the compositor request fractional scales. If the given wl_surface already has a wp_fractional_scale_v1 object associated, the fractional_scale_exists protocol error is raised. An additional interface to a wl_surface object which allows the compositor to inform the client of the preferred scale. The associated wl_surface's fractional scale object is destroyed. Notification of a new preferred scale for this surface that the compositor suggests that the client should use.